17.—Carnelian.
Occurs in masses or pebbles; at first grayish, but by exposure to the sun becomes uniform flesh, red or brown, never striped,—although Carnelian may form one of the bands of an Agate; brittle, breaking with a curved surface; very hard; takes a fine polish; glassy or resinous lustre; gravity 2.6.
Value.—Used for jewelry. When of two layers, white and red, (properly called sardonyx,) it is used for cameos.
Localities.—Same as Agate.